The invention relates to a steering control system for a tracked vehicle.
A tracked vehicle steering system is described in U.S. patent application Ser. No. 08/795,091, filed Feb. 5, 1997 and assigned to the assignee of this application. In this system a gear lever is movable between park, neutral and forward and reverse gear positions. The steering wheel is spring centered and is turnable in either direction to endstop positions. There is also an electronic steering wheel position sensor which generates an absolute steering wheel position signal. A microprocessor-based control unit controls vehicle steering as a function of the sensed steering wheel position, the gear lever position and other inputs. Such a tracked vehicle is intended to turn, or counter-rotate, without having any forward or reverse velocity. Also in this system the steering function is disabled electronically when the gear lever is in the park position and the vehicle is stationary. It would be undesirable for the vehicle to begin to turn immediately upon moving the gear lever from park to neutral or from park to neutral to gear with the transmission clutch disengaged if the steering wheel is not in its spring centered position. In addition, it would be undesirable to require the operator to simply re-center the steering wheel before steering is enabled. Yet, it is desirable to permit steering to function while the gear lever is in neutral or in gear when the vehicle is stationary. Thus, it is desirable to provide a tracked vehicle steering system disables steering during movement of the gear lever from park to neutral or from park to neutral to gear regardless of steering wheel position, but give an operator full turning capability without having to re-center the steering wheel.